Like a zombie ambling toward its target, Brad Pitt took his time developing "World War Z." Plan B, his production company, first acquired the rights to Max Brooks' novel about the rise of the flesh-eating undead in 2007, then hiring "Quantum of Solace" director Marc Forster to helm the project before the script underwent a series of rewrites.

At that point, it was not at all clear that Pitt would take on anything more than a behind-the-scenes role. Eventually, though, Forster found in Pitt not only a hands-on producer but the star of his film.

"I was really intrigued by the book," Forster told MTV News at the Toronto International Film Festival while promoting his drama, "Machine Gun Preacher." "I always wanted to work with [Pitt]. I think he is an incredible actor and he is an inspiring collaborator. If you look at his filmography, he has incredibly good taste. The choices he makes — he's very smart about it."

The book itself doesn't present a straightforward narrative, but an oral history that skips from character to character and crumbling nation to crumbling nation as the zombie apocalypse takes hold. From these far-flung plot strands, the filmmakers had to construct a coherent, streamlined narrative. What's more, they had to find a way to separate "World War Z" from the zombie-centric pack, both past and present, in movies, TV, video games and beyond.

"You want to try to avoid the cliché, try to make something interesting that hasn't been done before, and I felt [Pitt] was the right collaborator for that," Forster said.

Doing something fresh, in this case, meant creating something new: The film trades an oral history approach for a focus on Pitt's globe-hopping United Nations employee. "He's someone who works in the UN, has been in a lot of the hotspots around the world, from Bosnia to Sarajevo to Somalia, and has been able to stay alive," Forster said. "In this extraordinary circumstance, his journey is to basically stay alive so that the audience can keep enjoying the movie. He is trying to get to the root of how it started and to maybe find a way to beat it."